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UNIVERSITI PUTRA MALAYSIA

CRYSTALLIZATION OF PALM OIL-BASED 9,10-DIHYDROXYSTEARIC

ACID EMPLOYING ISOPROPYL ALCOHOL AS SOLVENT

GREGORY KOAY FENG LING

FK 2007 23

CRYSTALLIZATION OF PALM OIL-BASED 9,10-DIHYDROXYSTEARIC ACID EMPLOYING ISOPROPYL ALCOHOL AS SOLVENT

By


Thesis Submitted to the School of Graduate Studies, Universiti Putra Malaysia, in Fulfilment of the Requirements for the Degree of Master of Science

April 2007

ii

This thesis is specially dedicated to My beloved parents, Stanislaus and Agnes

My siblings, Anthony and Clement &

All my love ones For standing by me through thick and thin

iii

Abstract of thesis presented to the Senate of Universiti Putra Malaysia in fulfilment of the requirement for the degree of Master of Science

CRYSTALLIZATION OF PALM OIL-BASED 9,10-DIHYDROXYSTEARIC

ACID EMPLOYING ISOPROPYL ALCOHOL AS SOLVENT

By


April 2007

Chairman: Associate Professor Luqman Chuah Abdullah, PhD Faculty: Engineering 9,10-dihydroxystearic acid (DHSA) was derived from commercial grade palm oil based

crude oleic acid. It was derived through the epoxidation of the unsaturation present in

the oleic acid with performic acid in the presence of sulphuric acid and hydrogen

peroxide, followed with in-situ hydrolysis of the epoxide with hydrogen donor such as

water. DHSA promises great potential in the personal care industry. It has the

prospective to act as a multipurpose intermediate in the synthesis of fine chemical

products such as decorative cosmetics. However, the impurities present in DHSA could

lead to skin irritation and thus the crude DHSA produced need to endure purification

process in order to be qualified as an additive for the cosmetic industry. Solvent

crystallization was chosen as the path in preparing DHSA crystals of at least 80% purity

and of high desirability.

The objective of this research was to study the effects of temperature and of solvent

quality and quantity on the solvent crystallization of DHSA. On detailing the effects of

temperature, four aspects were scrutinized: weight based crystal yield, particle size

iv

distribution (PSD), quality of purified DHSA crystals and crystallization operation

efficiency. PSD, crystal morphology and quality of purified DHSA crystals were

scrutinized when detailing the effects of solvent quality and quantity.

In the course of carrying out the research work, a crystallization unit was fabricated.

The detailed design and operation of the crystallization unit were described. This

research, through gas chromatography (GC), PSD, Fourier Transform – Infra Red (FT-

IR) and scanning electron microscopy (SEM) analysis, revealed that solvent

crystallization of DHSA was best carried out with the cooling temperature of 20°C, 80%

isopropyl alcohol (IPA) concentration and solventacid tearicdihydroxys crude ratio of 1.0:1.0.

v

Abstrak tesis yang dikemukakan kepada Senat Universiti Putra Malaysia sebagai memenuhi keperluan untuk ijazah Master Sains

PENGHABLURAN ASID 9,10-DIHIDROKSISTEARIK BERASASKAN

MINYAK SAWIT MENGGUNAKAN ISOPROPIL ALKOHOL SEBAGAI PELARUT

Oleh


April 2007

Pengerusi: Profesor Madya Luqman Chuah Abdullah, PhD Fakulti: Kejuruteraan Asid 9,10-dihidroksistearik (DHSA) dihasilkan daripada asid oleik mentah yang

berasaskan minyak sawit bergred dagangan. Ia dihasilkan melalui proses

mengepoksidasikan ketidaktepuan yang wujud dalam asid oleik dengan asid performik.

Proses ini dijalankan dalam kehadiran asid sulfurik dan hidrogen peroksida. Seterusnya,

proses hidrolisis dijalankan secara in-situ keatas epoksida yang terhasil dengan

penderma hidrogen seperti air. DHSA mempunyai potensi yang baik dalam industri

penghasilan barangan penjagaan diri. Ia mempunyai prospek untuk menjadi pengantara

pelbagaiguna dalam sintesis bahan kimia halus seperti bahan kosmetik untuk tujuan

perhiasan diri. Namun, bahan cemar yang hadir boleh mengakibatkan kesan sampingan.

Oleh itu, DHSA mentah perlu dinyahcemarkan supaya ia boleh digunakan sebagai aditif

dalam industri kosmetik. Proses penghabluran dengan bantuan pelarut telah dipilih

untuk menghasilkan hablur DHSA berketulenan 80% dan ke atas serta mempunyai

permintaan yang tinggi dalam pasaran.

vi

Objektif kajian ini ialah untuk mengkaji kesan suhu dan kesan kualiti dan kuantiti bahan

pelarut ke atas penghabluran DHSA. Dalam mengkaji kesan suhu, empat aspek telah

diperinci: jumlah penghasilan hablur, taburan saiz zarah (PSD), kualiti hablur DHSA

yang telah ditulenkan dan kecekapan operasi penghabluran. PSD, morfologi hablur dan

kualiti hablur DHSA diperinci semasa mengkaji kesan kualiti dan kuantiti bahan pelarut.

Dalam pada menjalankan kerja kajian ini, seunit mesin penghablur telah dibina.

Rekabentuk dan cara mengoperasikan mesin penghablur ini telah diterangkan secara

terperinci. Analisis kromatografi gas (GC), PSD, Penukaran Fourier – Infra Merah (FT-

IR) dan penelitian mikroskopi dengan elektron (SEM), menunjukkan bahawa

penghabluran DHSA paling sesuai dijalankan pada suhu 20°C dengan alkohol isopropil

berkepekatan 80% dan DHSA mentah:bahan pelarut bernisbah 1.0:1.0.

vii

ACKNOWLEDGEMENTS

First and foremost, I would like to thank my advisor and chairman of the supervisory

committee, Assoc. Prof. Dr. Luqman Chuah Abdullah, my supervisory committee

members Assoc. Prof. Dr. Thomas Choong Shean Yaw, Dr. Salmiah Ahmad and Ir.

Parthiban Siwayanan for constantly guiding and encouraging me throughout this

research. Thanks for your advice and suggestion. Without you, this thesis could not

have reached its final form.

I would also like to extend my thanks to all the staff members of Department of

Chemical and Environmental Engineering, UPM, of School of Graduate Studies, UPM

and of Advanced Oleochemical Technology Division, MPOB, especially for the

professional and technical assistance rendered.

Last but not least, I thank my parents, siblings, all my family members and all my love

ones for their continuous prayers, love and support throughout my course of study.

viii

I certify that an Examination Committee has met on 18 April 2007 to conduct the final examination of Gregory Koay Feng Ling on his Master of Science thesis entitled “Crystallization of Palm Oil-Based 9,10-Dihydroxystearic Acid Employing Isopropyl Alcohol as Solvent” in accordance with Universiti Pertanian Malaysia (Higher Degree) Act 1980 and Universiti Pertanian Malaysia (Higher Degree) Regulations 1981. The Committee recommends that the candidate be awarded the relevant degree. Members of the Examination Committee are as follows: Azni Idris, PhD Professor Faculty of Engineering Universiti Putra Malaysia (Chairman) Sa’ari Mustapha, PhD Associate Professor Faculty of Engineering Universiti Putra Malaysia (Internal Examiner) Tinia Idaty Mohd Ghazi, PhD Lecturer Faculty of Engineering Universiti Putra Malaysia (Internal Examiner) Mohd Sobri Takriff, PhD Associate Professor Faculty of Engineering Universiti Kebangsaan Malaysia (External Examiner)

________________________________ HASANAH MOHD. GHAZALI, PhD Professor/Deputy Dean School of Graduate Studies Universiti Putra Malaysia

Date: 21 JUNE 2007

ix

This thesis submitted to the Senate of Universiti Putra Malaysia and has been accepted as fulfilment of the requirement for the degree of Master of Science. The members of the Supervisory Committee are as follows: Luqman Chuah Abdullah, PhD Associate Professor Faculty of Engineering Universiti Putra Malaysia (Chairman) Thomas Choong Shean Yaw, PhD Associate Professor Faculty of Engineering Universiti Putra Malaysia (Member) Salmiah Ahmad, PhD Deputy Director General (Services) Malaysian Palm Oil Board (Member)

____________________________ AINI IDERIS, PhD Professor/Dean School of Graduate Studies Universiti Putra Malaysia

Date: 17 JULY 2007

x

DECLARATION

I hereby declare that the thesis is based on my original work except for quotations and citations which have been duly acknowledged. I also declare that it has not been previously or concurrently submitted for any other degree at UPM or other institutions.

_____________________________ GREGORY KOAY FENG LING

Date: 28 DECEMBER 2006

xi

TABLE OF CONTENTS

Page DEDICATION ii ABSTRACT iii ABSTRAK v ACKNOWLEDGEMENTS vii APPROVAL viii DECLARATION x LIST OF TABLES xiii LIST OF FIGURES xiv LIST OF ABBREVIATIONS xvii CHAPTER 1 INTRODUCTION 1.1 1.1 Oleochemical 1.1 1.2 Fatty Acids 1.1 1.3 Palm Oil and Palm Kernel Oil as Sources of Fatty Acids 1.2 1.4 Hydroxyl Fatty Acids 1.5 1.5 Dihydroxystearic Acid (DHSA) 1.6 1.6 Crystallization 1.9 1.7 Crystallization in Palm Oil Industry 1.11 1.8 Crystallization of DHSA 1.12 1.9 Problem Statements 1.12 1.10 Objectives 1.13 1.11 Scope of Research 1.14 2 LITERATURE REVIEW 2.1 2.1 Oils and Fats 2.1 2.2 Fatty Acids in Oils and Fats 2.3 2.3 Crystallization of Oils and Fats 2.6 2.4 Phase Behavior 2.10 2.5 Supersaturation 2.13 2.6 Nucleation 2.17 2.7 Crystal Growth 2.18 2.8 Crystal Size and Shape 2.22 2.9 Kinetics of Crystallization 2.25 2.10 Crystal Size Distribution 2.29 2.11 Filtration Method 2.34 2.12 Dihydroxystearic Acid (DHSA) 2.36

xii

3 METHODOLOGY 3.1 3.1 Preparation of Crude DHSA 3.1 3.2 Equipment Design 3.5 3.3 Operation of Crystallization Unit 3.11 3.4 Experimental Methods 3.17 3.5 Analytical Methods 3.22 3.5.1 Gas Chromatography Analysis 3.22 3.5.2 Particle Size Distribution Analysis 3.24 3.5.3 Fourier Transform – Infra Red Analysis 3.25 3.5.4 Scanning Electron Microscopy Analysis 3.25 3.5.5 X-Ray Diffraction Analysis 3.26 3.6 Overall Crystallization Operation Efficiency 3.27 4 RESULTS AND DISCUSSION 4.1 4.1 Effects of Temperature in the Crystallization of DHSA 4.1 4.1.1 Sectional Introduction 4.1 4.1.2 Effects of Temperature on Weight Based

Crystal Yield 4.2

4.1.3 Effects of Temperature on Particle Size Distribution

4.9

4.1.4 Effects of Temperature on Quality of Purified DHSA Crystals

4.14

4.1.5 Effects of Temperature on Crystallization Operation Efficiency

4.17

4.1.6 Sectional Summary 4.19 4.2 Effects of Solvent Quality and Quantity in the

Crystallization of DHSA 4.20

4.2.1 Sectional Introduction 4.20 4.2.2 Effects of Solvent Quality and Quantity on

Particle Size Distribution 4.21

4.2.3 Effects of Solvent Quality and Quantity on Crystal Morphology

4.27

4.2.4 Effects of Solvent Quality and Quantity on Quality of Purified DHSA Crystals

4.32

4.2.5 Sectional Summary 4.35 5 CONCLUSION 5.1 5.1 Conclusion 5.1 5.2 Future Studies 5.2 REFERENCES R.1 APPENDICES A.1 BIODATA OF THE AUTHOR B.1

xiii

LIST OF TABLES

Table

Page

1.1

Malaysian annual production of oil palm products for 1975 – 2004 1.4

1.2

Fatty acid composition of palm oil 1.6

1.3

Application and/or functionalities of DHSA in the personal care finish products

1.8

1.4

Classification of crystallizing equipment 1.10

2.1

Typical fatty acids found in oils and fats 2.3

2.2

Definitions of particle shape 2.24

2.3

Definitions of particle size 2.30

3.1

Basic properties of the chemicals used in the preparation of crude DHSA

3.2

3.2

Summary of the detailed specification of the crystallization unit 3.9

3.3

The function of the parameters keyed-in into the crystallization unit control system

3.11

3.4

Theoretical composition of the mixture present in the crystallization vessel

3.18

3.5

Comparison of crystallization method from MPOB and this research 3.22

4.1

Comparison of averaged median particle size, volume weighted mean diameter, D [4,3], and surface weighted mean diameter, D [3,2], of the DHSA crystal particles formed at various operating parameters

4.14

4.2

The overall efficiency of the DHSA crystallization operation employing IPA as solvent

4.18

4.3

Standard deviation of the DHSA crystals’ distribution curve generated as a result of operating under different parameters

4.25

4.4

Readings of XRD analysis on DHSA 4.31

xiv

LIST OF FIGURES

Figure

Page

1.1

DHSA formation process from oleic acid 1.7

2.1

TAG with different fatty acid positions 2.2

2.2

The cis- and trans- configurations of fatty acids 2.5

2.3

The influence diagram of interrelationship among key factors that impact a crystallization process

2.7

2.4

Typical agitated batch crystallizers 2.9

2.5

Eutectic phase diagram 2.11

2.6

Solid solution phase diagram 2.12

2.7

Saturation-supersaturation curve 2.14

2.8

Growth rate versus supersaturation curves for three different growth mechanisms

2.20

2.9

Number-frequency histogram 2.31

2.10

The relative percentage frequency distribution by number 2.31

2.11

A log-normal distribution plotted as a relative percentage frequency distribution using a logarithmic scale for particle size

2.32

3.1

Reaction path of the preparation of DHSA from oleic acid 3.4

3.2

The crystallization unit with the internal structure exposed 3.6

3.3

The process tank of the crystallization unit 3.7

3.4

The three mixer head attached to the crystallization unit 3.8

3.5

General layout of the crystallization unit 3.10

3.6

Temperature profile of the entire operation duration of the crystallization unit

3.12

3.7

First display of the color touch screen – main screen 3.13

xv

3.8

Second display of the color touch screen – program screen 3.14

3.9

Third display of the color touch screen – service screen 3.14

3.10

Fourth display of the color touch screen – trending screen 3.15

3.11

Zoom in on the saw-tooth structure of the process tank rim 3.17

3.12

Flow chart of experimental procedure and order of research event 3.21

4.1

The temperature profiles for the entire process of the crystallization operations employing three different cooling temperatures, 20°C, 25°C and 30°C

4.3

4.2

The contrast between weight based percentage of crystals yielded from crude DHSA for different cooling temperatures and different IPA concentrations

4.4

4.3

GC separation spectrum of the components of DHSA prepared from commercial grade palm oil based crude oleic acid – Crude DHSA

4.7

4.4

Statistical graph of the PSD of the DHSA crystals produced with 70% IPA concentration at 20°C cooling temperature

4.9

4.5


4.9

4.6


4.10

4.7


4.10

4.8


4.11

4.9


4.11

4.10


4.12

4.11


4.12

xvi

4.12


4.13

4.13

GC separation spectrum of the components of DHSA prepared from commercial grade palm oil based crude oleic acid – Purified DHSA

4.15

4.14

The contrast between the percentage of purity of purified DHSA crystals yielded under different cooling temperatures and different IPA concentrations

4.15

4.15

Statistical graph of the PSD of the DHSA crystals produced with 70% IPA concentration with solvent

acid tearicdihydroxys crude ratio of 1.5:1.0 4.22

4.16



4.17



4.18



4.19



4.20



4.21

SEM image of DHSA crystal particles produced with 80% IPA concentration coupled with solvent


4.22



4.23



4.24

FT-IR spectrum for crude DHSA 4.30

4.25

Typical FT-IR spectrum for purified DHSA crystals 4.30

4.26 The contrast between the percentage of purity of purified DHSA crystals yielded under different solvent

acid tearicdihydroxys crude weight over weight ratios and different IPA concentrations

4.33

xvii

LIST OF ABBREVIATIONS

AOTD Advanced Oleochemical Technology Division

BTSFA Bis(trimethylsilyl)trifluoroacetamide

CSD Crystal size distribution

CSTR Continuous stir tank reactor

DHSA Dihydroxystearic acid

DMF N,N-Dimethylformamide

D [3,2] Surface weighted mean diameter

D [4,3] Volume weighted mean diameter

FFA Free fatty acids

FT-IR Fourier Transform – Infra Red

G Growth rate

GC Gas chromatography

HCOOH Performic acid

H2O2 Hydrogen peroxide

H2SO4 Sulphuric acid

IPA Isopropyl alcohol

J Nucleation rate

+iJ Adsorption rate of component i

−iJ Desorption rate of component i

KBr Potassium bromide

KCl Potassium chloride

xviii

KNO3 Potassium nitrate

LD Lag time

Ls Steady state geometric mean crystal diameter

L’(t) Geometric mean size of fat crystals’ size distribution with time

MPOB Malaysian Palm Oil Board

N Population density

NaCl Sodium chloride

Na2SO4 Sodium sulphate or sodium sulphate anhydrous

PKO Palm kernel oil

PSD Particle size distribution

RI Reflective index

Rt Retention time

SEM Scanning electron microscopy

TAG Triacylglycerols

Tc Crystallization temperature

TMS Trimethylsilyl

Tm (K) or Tm Melting point or melting temperature

Xi Average mesh size

XRD X-ray diffraction

-aeq Chemical activity at equilibrium state

-ass Chemical activity at supersaturated state

-dv Volume diameter

-ds Surface diameter

xix

-dsv Surface volume diameter

-dd Drag diameter

-df Free falling diameter

-dSt Stokes’ diameter

-da or -dp Projected area diameter

-dc Perimeter diameter

-dA Sieve diameter

-dF Feret’s diameter

-dM Martin’s diameter

-dR Unrolled diameter

-hi Induction time

-ki Volume percent

-n Number density per volume of crystals or total volume percent, 100

-s Standard deviation

-smax Maximum fraction of solid fat

-s(t) Fraction of solid fat at time t

-x Solubility of solute at temperature T (K)

-xeq Chemical activity of ideal solution at equilibrium state

-xss Chemical activity of ideal solution at supersaturated state

lix Molar fraction of component i at arbitrary point

leqix , Molar fraction of component i at equilibrium liquid state

six Concentration of component i at solid surface

xx

sjx Concentration of component j at solid surface

-∆Gc Activation free energy of nucleation

-∆Gd Activation free energy of diffusion

∆H Change in enthalpy

-∆Hm Molar heat of melting

∆T Supercooling value

-λ Nominal induction time

-µ Maximum increase rate in fraction solid fat

-µeq Chemical potential at equilibrium state

-µss Chemical potential at supersaturated state

-ν Growth rate

-σ Supersaturation or crystal/melt interface free surface energy

-τc Time constant associated with crystallization

CHAPTER 1

INTRODUCTION

1.1 Oleochemicals

Oleochemicals are chemicals derived from biological oils and fats via the splitting of

triglycerides into their constituent fatty acid derivatives and glycerol or via modification

of oils and/or fats. The oils and/or fats may be of vegetable (e.g. castor oil, coconut oil,

corn oil, cottonseed oil, groundnut oil, linseed oil, olive oil, palm kernel oil (PKO), palm

oil, rapeseed oil, sesame oil, soybean oil, sunflower oil, etc.), animal (e.g. butter, lard

and grease, edible and non edible tallow, etc.) or marine (e.g. fish oil) origin.

Oleochemicals are analogous to petrochemicals. In other words, similar chemicals may

be synthesized from petroleum. The most basic oleochemicals are fatty acids, fatty

methyl esters, fatty alkyl esters, fatty alcohols, fatty amines and glycerol (Ahmad et al.,

2000a).

1.2 Fatty Acids

In chemistry, a fatty acid is a carboxylic acid. A fatty acid is characterized by the

number of carbon atoms in the carbon chain, ranging generally from caproic acid with

six carbon atoms to behenic acid with 22 carbon atoms. Most of the natural fatty acids

have an even number of carbon atoms. Fatty acids without double bonds are called

saturated fatty acids. They are generally solids (Dieckelmann and Heinz, 1988).

1. 2

Saturated fatty acids also do not contain other functional groups along the carbon chain.

The term ‘saturated’ refers to hydrogen, in that all carbons (apart from the carboxylic

acid [-COOH] group) contain as many hydrogen atoms as possible.

Fatty acids with double bonds are unsaturated and generally liquids (Dieckelmann and

Heinz, 1988). One or more alkene functional groups exist along the carbon chain, with

each alkene substituting a singly-bonded ‘-CH2-CH2-’ part of the chain with a doubly

bonded ‘-CH=CH-’ part. The two hydrogen atoms that are bound to the doubly bonded

carbon atoms can occur in either cis- or trans- configuration.

1.3 Palm Oil and Palm Kernel Oil as Sources of Fatty Acids

In tallow, C16 and C18 fatty acids dominate; in coconut oil, C12 and C14 acids are more

prevailing (Dieckelmann and Heinz, 1988). Thus, tallow and coconut oil are

traditionally used as feed stocks for oleochemicals of chain lengths 12, 14, 16, 18 and

18:1. Prior to 1985, tallow was an important raw material for the oleochemical industry.

However, during the period 1985-1995, the significance of tallow was greatly reduced.

This was due to the following three factors:

• Minimal increase in the world’s production (about 25% increase in 10 years);

• Suspected relationship between human disease and materials of animal origin

and thus, the reluctance of manufacturers to use tallow;

1. 3

• The negative perception among consumers on the use of animal derived

oleochemicals for consumer products, particularly in personal care products.

For the ensuing years, no increase or even a decrease in tallow production and use was

foreseen and it was expected that tallow would play a less important role in the

oleochemical industry in the future.

In a similar fashion, prior to 1985, coconut oil was the most important source of C12 and

C14 fatty acids for the oleochemical industry. However, during the period of 1985-1995,

the global production of coconut oil increased by only 10% and the production was not

expected to increase significantly in the foreseeable future. Thus, the significance of

coconut oil for the oleochemical industry was also expected to be diminished somewhat

in the future (Ahmad et al., 2000a).

For the corresponding period, both palm oil and PKO enjoyed steady and heartening

growth in Malaysia. In 1985, the production of crude palm oil and crude PKO stood at

4,134,463 and 511,908 tons per annum respectively and by the year 1994, the

production increased to 7,810,546 and 1,036,538 tons per annum respectively. There

was almost a 90% increase for crude palm oil production and over 100% increase for

crude PKO production. For the ensuing 10 years, the production increase was almost

80% for crude palm oil and almost 60% for crude PKO. In 2004, the production of

crude palm oil stood at 13,976,182 tons per annum while the production of crude PKO

1. 4

stood at 1,644,445 tons per annum (MPOB, 2005). The annual production of oil palm

products in Malaysia for the period 1975-2004 is shown in Table 1.1.

Table 1.1: Malaysian annual production of oil palm products for 1975 – 2004 (Malaysian Palm Oil Board – MPOB, 2005)

Year Crude palm oil (tons)

Crude PKO (tons)

1975 1,257,573 108,260 1980 2,573,173 222,285 1985 4,134,463 511,908 1990 6,094,622 827,233 1995 7,810,546 1,036,538 2000 10,842,095 1,384,685 2004 13,976,182 1,644,445

This mass production not only put Malaysia in the global map as both the world top

producer and exporter of palm oil but also as the world third major producer and top

exporter of 17 biological oils and fats besides elevating the status of palm oil as the

world second most produced biological oils and fats, ranking right behind soybean oil

(MPOB, 2005).

Insignificant increase in tallow production allowed the emergence of palm oil as a new

source of C16 and C18. As the centre of growth of oleochemicals gradually shifts to the

ASEAN region, palm oil would equally replace tallow and its usage would therefore

markedly increase (Yusof et al., 1996; Ahmad et al., 2000a). Coconut oil used to enjoy

a unique position in the oleochemical industry due to its fatty acid composition,

particularly lauric acid which is highly regarded in the cosmetics and detergent industry.

However, this position is threatened with the emergence of PKO as the sole alternative

source of commercially available lauric oils. For Malaysian oleochemical

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